Clinical and morphologic characteristics of the deciduous and permanent teeth of individuals affected with a wide variety of inherited or acquired metabolic diseases are studied. The gross and microscopic changes in the teeth are recorded, and correlations with the developmental events and general metabolic changes are undertaken. Teeth removed from patients with metabolic disease who have been studied at the Clinical Center of the National Institutes of Health, comprise the major source of material, although specimens from outside sources are studied as well. Disorders currently under study include: Hereditary hypophosphatemia (Vitamin D-resistant rickets), hypophosphatasia, pseudohypoparathyroidism, diabetes insipidus, ectodermal dysplasia, chronic Vitamin D intoxication, infantile hypercalcemia, primary hyperoxaluria, etc.